Metal working mechanism



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JNVENTOR. Yrzzf iiyama E. J. sVENsoN METAL. WORKING MECHANISM March l5,1960 10 Sheets-Sheet 3 Filed April so, 125e Y INVEN TOR. d'yafzaza Ia/wf@ ma V1" March l5, 1960 E, J, svENsoN I A2,928,297

METAL WORKING MECHANISM Filed April 30, 1956 10 ,Sheets-Sheet 4 44 236.33.43E-55 y E 4 Y l: l' E4 404; I Y '410, g/ 364 550 f 596594 E@ 704 57eE A @la l If- 72, I 106 K9 @E y 535 64 ff-f6 I I waz L Z56- March 15,1960 E. J. svENsoN METAL WORKING MECHANISM 1o sheets-sheet 5 Filed April50, 1956 IN VEN TOR. nasi fda/@migra /w am E. J. SVENSON METAL WORKINGIIECHANISM March l5, 1960 10 Sheets-Sheet 6 Filed April 30, 1956 Em?5.,. M Z E? i 9 2 1 M w 5 INVENTOR. f J. f vergab/0 UM ma@ March 15,1960 E. J. svENsoN 2,923,297

METAL. woRxING uEcHANIsu Filed April 30, 1956 10 Sheets-Sheet 7 f# E@M//M/ JS- March l5, 1960 E. J. svENsoN amm. wonxmc uEcHANIsM 1osheets-sheet a Filed April so, 195e March 15, 1960 E. J. svENsoN METALWORKING MECHANISM 10 Sheets-Sheet 9 Filed April 30, 1956 INVENTOR. if;naf fu/radom E. J. SVENSON METAL WORKING MECHANISM Marh 15, 1960 FiledApril 50, 1956 v10 Sheets-Sheet 10 M2/www 2,928,297 METAL WORKINGMECHANISM Ernest J. Svenson, Rockford, lll. A Appication April 30,1,956, Serial No. 581,557

6 claims. (ci. 'J7-33.5)

This invention relates to ajmetal lcutting mechanism or machine. Morespecically, the invention pertains to an automatic metal cuttingmachine-for drilling deep or long holes by step drilling. The latterterm refers to metal drilling in which a rotating drill is caused topenetrate a workpiece to a predetermined depth constituing a fraction ofthe desired hole and then'withdrawn cornpletely from the workpiece forcleaning of chips A.by a flowing coolant, this cycle of steps beingrepeated automatically until the hole is completed. Y

When the relative length or depthof a drilledhole is almost ten tothirty times (or more) greater lthan the diameter of the hole, drillingmust`be doneby the step drilling method, rather than by continuousdrilling, to provide for removalof the chips which otherwise would chokeup the drill and cause it toY break.

In drilling metal workpieces, the drill is notsubjected to constantresistance. The drill `will be worn asdrilling progresses, withresultant increased resistance to its.ro tation and to forward feedingthereof. The drill Vflutes may be partially packed with chips. Expansiondue to heating of the drill may cause added resistance tothe rotation ofthe drill. The resistance of the workpiecematerial may be subject tolocal variations.

These variations in resistance against drill movements could possibly becompensated for by providing sucient motive power to overcome thegreatest resistance to be overcome and by providing suiicient structuralstrength in the drill and the drill moving and supporting ,elements toinsure against breakage when overcoming the resistance-against drillmovement, if, and only if, there is sutlicient space available toaccommodate drill moving and supporting elements having the dimensionsrequired for such structural strength. In otherY words, it might bepossible to provide against overloads by increasing Vthe dimensions andthereby'the structural strength ofdrill moving and supporting elementswhen there are no space limitations prohibiting such large dimensions.

In many instances, as when six or eight oil holesare to be drilledsimultaneously in an automobile crank shaft, the available space doesnot permit the use'of a drill supporting and moving structure heavyenough to resist the overloads to which it will be subjected. Hence, ithas heretofore been customary to make the drill itself rather light, sothat it will break under an overload rather than the drill supporting ormoving element, with resultant frequent breakage of the drill. Attemptshave also been made to provide other protective means against overloads,but also with unsatisfactory results, for rea- .sons explainedhereinbelow.

In drilling a pluralityV of holes simultaneously in a singleV workpiece,such as an automobile crank shaft, it has been customary to actuate aplurality of drilling units 4from 'a single source of pressurizedhydraulic liui'd. At any given movement, one or more ysuch units may beremoving metal, others may be withdrawn from the workpiece for cleaningand cooling, and stillothers may be -appreaching the workpiece forresumption of metal removal f-nited States YPatent ICC' Yaftercleanin'gand'cooling. Obviously, under `'these#con ditions, no protection ofindividual drill unitsgagai'inst overload can be' had rby regulating theabove'noted single `source of pressurized hydraulic Huid. VVRecourse hasthere- Vfore'been had'to various mechanical devices associated with anindividual drilling unit, but so far suchmeclianical devices, althoughoperative to some extent, havefrit provided a completely satisfactorysolution to the problem in question, although this problem hasbeenrecognized bythe automobile industry forrmore than twenty years.

It should/be explained, in this connectionjthatftlie vdrills'in questionare conventionally rotated by V mechanifcallmeans' (which may beprovided separately lforieafcfh individual drilling unit) but'displacedlongitudinally (fr rapid traverse to, feeding-into orwith'draWalfrom-tle ".vorkpiece) by a uid motor actuated bypressurized'jhydraulic fluid. Thus, two sources of power, and/oritw'opower transmitting mechanisms mustbe controlled simultaneously and inproper relation to each other, if protection against overloads is to beeffected.

It is therefore an object of the present invention "to provide a metalworking machine for step drilling of relatively lightconstruction andoccupying a relativ`e1`y small space so that a plurality of suchmachines can ,be -used for simultaneously drilling holes in asingleWoi'k piece, this metal working machine beingautofmaticinlopperation and, in spite of its light construction, not'su'bjet tobreakage `ofeither the drill or drill supporting'orfmoving elements.

Another 'object of this invention isto 'provide a metalworking'machine'of'the type indicated comprisingv means for protecting'the machine against overloadswhichvcontrolboth a mechanical powertransmitting mechanism for rotating the drill and a hydraulic Vdevicefor advancing and withdrawing the drill.

A specic object of the present invention is to provide va metal workingmachine ofthe type indicated including a pump driven by the drillspindle so connectedtofa fluid motor for advancing lthe drill thatthe'hydraulic pressure for advancing the drill upon feeding movement ofthe drill will be furnished by said pump whereby'the Vfeed rate of thedrill per unit of drill rotation. wilt-.remain constant. In otherwords,.if drill rotation is slowed up, as when the drill becomes wornor. packed with chips, Y

drilldisplacement for segregating a part of saidhydraulicV systemincluding the pump to form a singleclosedeirfcuit upon advancement ofthe drill to feeding position.

Another specic object of the present invention is to provide ametalworking machine of thetype-indicated including protective devicesresponsive both to ltorque 'overloads and to thrust overloads andoperative to withdraw the drill from the work piece wheneveroverloadsfare encountered. Other and further Yobjects and features ofthis invention will become apparent from the following disclospre andappended claims as illustrated bythe accompanying drawings wherein thesame numerals indicate-identical parts, and in which:

'Figure 1 is a side elevational view of a drilling nur chine accordingto the Vpresent invention, with-.parts broken away; Y

FigureV 2 is an Yenlarged end elevationalview taken along line 2 2 ofFigure l, with parts broken away;-

Figure 3 is an enlarged side 'elevational vieu/ofthe front portion ofthe machine of Figure 1 taken along aaaasov f.

the line 3 3` of Figure 2 and showing the opposite side 'of that shownin Figure 1, parts being Vshown in vertical section and other partsbeing broken away;

Figure 4 is a greatly enlarged fragmentary cross Sectional view of arear portion `of the machine'of AFigure l *taken along the plane of line5 5 of Figure 2, partsbeing Shown in elevation;

Figure 5 is a greatly enlarged fragmentary cross sectional view of afront portion of the machine of Figure p 1 taken along the line 5 5 ofFigure 2, parts being shown in elevation;

Figure 6 is a greatly enlarged fragmentary plan view ofa middle portionof the machine of Figure l taken alongtheline 6 6 of Figure 1, partsbeing shown in horizontal section and other parts being broken away;Figure `7 is a greatly enlarged fragmentary plan view oiga' `frontportion ofthe machine of Figure 1, taken valong' the line 7 7 of Figure2, partsy being shown in horizontal section and other parts being brokenaway; Y

Figure 8 is a greatly enlarged fragmentary cross sectional view takenalongthe line 8 8 of Figure 7;

Figure 9 isf a greatly enlarged fragmentary cross sec- ."tional viewtaken along the line 9 9 of Figure 7;

VFigure 10 is Va greatly enlarged fragmentary cross sectional view takenalong the line 10-10 of Figure 4;

Figure 1l"is a greatly enlarged fragmentary cross sectional view takenalong the line 11 11 of Figure 10;

Figure `12 is a greatly enlarged fragmentary cross sectional view takenalong the line 12-12 of Figure 10; Figure 13 is a greatly enlargedfragmentary cross Sectional viewtaken'along the line 13 13 of Figure 10;

' Figure 14 is a diagrammatic representation of a charge control valveshown in vertical section and a solenoid associated therewith, thehousing for said valve-solenoid y sectional view taken along the line 1515 of Figure 18; Y

--Figure F16 is a greatly enlarged fragmentary cross sectional viewtaken along the line 16 16 of `Figure 18;

Figure 17 is a greatly enlarged fragmentary cross sectional'view takenalong the line 17 17 of `Figure 18; l Figure 18 is a greatly enlargedfragmentary side elevational view similar to Figure 1` but showing onlya valve cluster and av lter forming part of the machine of Figure 1; Y

I Figure 419 is a greatly enlarged fragmentary cross sectional viewtaken along the line 19 19 of Figure 7, with parts broken away;

Figure 2O is -a greatly enlarged fragmentary cross sectional view takenalong the line 20-20 of Figure 19,

with'parts broken away;

Figure 21 is a greatly enlarged fragmentary cross sectional `view takenalong the line 21-21 of'Figure 19, with parts broken away; Y

`Figure 22 is a wholly diagrammatic representation 4of the main c ontrolvalve of the machine of Figure 1,"show ing said valve :in centralvertical cross section and in neutral position;

Figure 23'is a view similar to Figure 22 but showing said valve in rapidapproach position;

Figure 24 is a view similar to Figure 22 but showing said valve in feedposition;

Figure 25 is a view similar to Figure 22 but showing said valve in rapidreturn position;

Figure 26 is a wholly diagrammatic representation of the hydraulicsystem of the machine of Figure 1;

`Figure 27 is a partial side elevational view of an automobile crankshaft forming a work piece for drilling by the machine of Figure 1;

Figure 28 is a fragmentary view taken along the line 28 28 of Figure 29;j

IFigure 29 is an enlarged cross sectional view taken along the line29-29 of Figure 27; and

Figure 30 is an enlarged OSS sectional view taken" along the line 30-30of Figure 2,7,

' GENERAL DESCRIPTION Referring now to Figs. 1 and 2, a machinegenerally indicated at 10 includes a base 12 slidably supporting, on alongitudinal dovetail guide way 14, a drill head carrier 16 having adepending guide 18 received in the guide way 14. A gib 20 may beprovided between the walls of the guide way 14 and the guide 18. Agenerally tubular ram drill headr22 is slidably supported on ahorizontalbead 24 on` the carrier 16 which bed is recessed lengthwise todeneva dovetail guide way 26 receiving a guide` -28 depending from thedrill head 22. Another gib 30 may be provided between the walls of theguide way 26`and the guide 28. r

A drill spindle 32.isrotatably supported (see Fig. 5) within the ramdrill head 22 by front and rear ball bearings 34 and 36 and is alsoprovided with appropriate means, such as a socket 38, for attaching atool, for instance, a drill 40, at its projecting end. The outer race ofthe front hearing 34 is locked to the drill head 22 by being clamped'between an internal radial drill head shoulder'42 landa; nut 44 engagingscrew threads in the front end of the drill `head 22. The` inner race isclamped between a radial shoulder` 46 defined in the drill lspindle 32by the socket 38 and a nut 48 engaging screw threads on the'spindle 32.Thus, the front bearingV 34 carries the thrust when the ram drill head22 is moved forwardly in a drilling operation while permitting thespindle 32 to rotate. The outer race of the rear bearing 3 6 `is clampedagainst a second internal radial shoulder 50 at therear ofthe `dr`il1head 22 by means of a retainer 52 engaging internal screw threads in therear of the` drill head22. The 'rear Vbearing 36 carries a portion ofany `radial load which might be applied to the spindle 32 and insuresthat the rotation of the spindle 32 will always take place about itsaxis.

Referring now to FigHl, the spindle 32 is driven by forcetransmittedfrom a' primey mover, such as an electric Vmotor 54adjustably :mounted on a bracket 56 extending having an outer race V68and an inner race 70. The

outer race 68 is received within an internal recess in the sheave 62 andabuts against an internal radial shoulder 72 formedatthe rear `of thesaid recess inthe sheave 62,Y while .the inner race'70 abuts against ,afcollar 74 definedA on thesleeve 66being held againstv this collar by anut 76 `engaging screwthreads on the sleeve 66. The sleeve 66' isrotatable with, but slidable lengthwise Vofthe spindle 32, the'sleeve 66and the spindle 32 being connected by means of splinesg78 on the spindle32 and keys 79jon theinsidej of the` sleeve 66. A driving connectionbetween the sheave 62 and the sleeve 66 is provided by `a, torqueresponsive safety overload clutch `including parts described as follows,reference being made to Figs.l4` and 6. A plurality of camrsurfaces 80`are Vformed on the radial face of a restricted portion 82 .ofjYtheysheave 62 extending rearwardly therefrom. A

generally tubular member or sleeve 84 axiallyslidable on the sleeve 66but held for rotation therewith by a key 86 carries a plurality ofradially extending shafts 88. equal in n umber` to the cam 'surface 80.`On each ofwthese' shafts there is mounted a bearing 90 which carriesaroller or cam follower 92. Contact between the surfaces and the camfollowers 92 is maintained by aspring 94 compressed'betwee'n the tubularmember or` sleeve 84 and aV collar 96 screwed onto `the rear of thesleeve 66. o l

Thezabove disclosed torque responsive overload releaseV clutch.functions as follows. AAs the sheave V62 isL drivel? from thmvtcr 5.4,.the cam faces 80 are in engigement with the cain followers 9.2.

aangaat AThe force. trailsmitted from the cam faces f80 causes thefollowers 92 to move circumferentially, transferring this rotativemotion to the sleeve 8.4 which, through the ,action of the icey S6,causes the sleeve 66 to rotate and thereby also the spindle `32connected tothe sleeve 66 bythe splines 7 8gandykeys 79.

1f the drill 40 or other tool carried by the spindle32 encountersopposition to its rotation by reason of the tool being dull or beingclogged or being expanded by heat generated on drilling or due tovariationsin the material being worked, then a portion of the forcetransmitted between the cam faces 80 and the camfollowers 9,2 will beresolved along lines parallel to the axis of Vspindle rotation causingthe sleeve 84 to move axially against the force of the spring 94. Whenthe sleeve 84 has moved axially ksuciently far, Aa collar 918 thereoncontacts the actuating member 100 of an electrical switch V10,2 which,as described hereinbelow, on actuation will cause return of the r'arndrill head 22 and withdrawal of the tool from the work. Thus, breakageof the tool on excessive resistance to driving torque is avoided. Notethat the force of the spring 94 can be varied to provide for withdrawalsat various driving torques depending on the strength of the particulartool being used and on the nature of the work being drilled.

Axial movement of the drill head 22 is effected by means of a 'Huidmotor indicated generally at 103 and shown in Figs. 5, 8 and 9 asincluding a cylinder 4body 104 mounted in the drill head carrier 16below the bed 2 4.V Thecylinder body 104 is formed with an internal`bore 106 vreceivin"7 a piston 10S which carries on its circumference anumber of sealing rings 110 serving to prevent leakage of hydraulictluid pastthe piston. Further, the piston 108 is lixedly attached to arod 112 by'being looked between a radial vshoulder 114 formed near oneend of the rod and anut 116, threaded onto said end of the rod '112. Therear end ofthe cylinder body 104 is completely closed by an end cap 113and a sealing ring 120 associated therewith. The piston rod 112 projectsout of the cylinder body at the other end thereof, which other end issealed by a cap 122, a sealing ring 124 being disposed between the cap122 and the cylinder body 104 and a packing member 126 being disposedbetween the cap 122 and the piston rod 112. The sealing action of thepacking `124 may be adjusted by an externally threaded nut 12S engaginginternal threads in the cap 12,2; The projecting end of the piston rod112 is fixedly attached to a bracket or projection 130 depending fromthe drill head 22 which projection may be locked between a radialshoulder 132 near the projecting end of the rod 112 and a nut 134threaded on this end of the said rod.

The cylinder body Y106 is provided, near its ends, with ports connectedto conduits 136 and 13S for the flow of hydraulic iluid into and out ofthe bore 106, which fluid, acting on the piston 108 connected to thedrill head 22 through the piston rod 112 and the projection 130, causesthe drill head 22 to be dispaced axially relativev to the drill headcarrier 16 in which the cylinder body 10'4 is fixed. Note that on suchdisplacement the spindle 32 is displaced axially-along with the ramdrill head 22, while the sleeve 66 remains stationary.

Pump structure V6 Y spindle 32 is supported Vin front of the sheave 62r'by a pair of ball bearings 142 and A144 disposed within .an aperture`in a column 146 projecting upwardly from the drill head carrier 16. Theinner race of the bearing 142 abuts against the collar 74 on the sleeve66 while the inner race of the bearing 144 is held in place by a splitring 148 inserted in a circumferential groove in the sleeve 66. Theouter race of the bearing 142 abuts against Va retainer 150 attached tothe column 146 by screws 152. The outer race of the bearing 144 abutsagainst the radial face of a circular ilange 153 projecting from therear of a hollow pump housing 154 attached to the column 146, as by pins155. The spaces between the outer and inner races of the bearings 142and 144 lare sealed by annular members 156.

In front of the ring 1.48 the sleve 66 is restricted eccentrically asshown in Figs. 4 and 1Q to dene an actuating cam 158 for the pump 140.An anti-friction bearing unit including rollers 160 and an outer race162 is mounted over this eccentrically Vrestricted portion of the sleeve66. The rear of the race 162 abuts the radial shoulder defined by saideccentric restriction. The sleeve 66 terminates within the pump housing140, the terminal portion being restricted concentrically past the saideccentric restriction and having a collar 164 near its end formed withan axial ange 166. Rings 168 and 170 extend around the concentricallyconstricted portion of the sleeve 66 spaced by an intermediate splitring 172 fitting into a Vcircumferential groove in the sleeve 66. Therings 168 and 170 abut respectively against the front of the race 162and the free end of the ange 166 and-thereby hold the race 162 againstdisplacement. 'p

The pump housing 140 is formed ,at its forward end with an inturnedradial flange having a terminal surface 174 connected to the collar 164by an oil seal structure including an annulus 176 having o ne peripheralkend surface contacting the housing surface 174 withfthe end of theannulus abutting against a split ring 178` seated in a circumferentialgroove in the surface 174. At its other end the annulus 176 is offsetradially inwardly at the inner end of the surface 174 to overlie the endof the sleeve collar 164 and the free end of the annulus projectingwithin the pump housing 140 is deflected inwardly to overlie the insideofthe sleeve flange 166. A ring of L-shaped cross section has a rst leg180 contacting the inside of the annulus 176, and a second leg182'projecting radially inwardly and abutting the split ring 178.Another ring 184 has one kend seated on the inside of the annulus 176clamped between the deected shoulder of this -annulus and the end of thesaid rst leg 180 of the L-shaped ring, the ring 184Y being offsetslightly toward the second or projecting leg 1.82 of the L-shaped ring.A coil spring 186 is disposed between thelprojecting leg 182 of theL-shaped ring and the ring k134,

the spring pressure being transmitted by the ring 184 to an vannularpacking member 188 extendingV around the'V end of the sleeve 66 betweenthe ring 134. V

.The operatingparts ofthe pump 140 are described as follows, again withreference to Figs. 4, .10,111, 12 and 13. An inlet channel 190 lforhydraulic fluid delivered under pressurel from a conduit 19,2 extendstransversely through the pump housing 154 below the hollow interiorthereof, and this channel 190 terminates blind short of the oppositeside of the housing 154. Two parallel vertithe sleeve collar 166 and calchannels 194 and 196 afford communication betweenV the channel 190 andtwo vertically disposed check valves As will be disclosed indicatedgenerally at 198 and 200. The va1ve198includes a valve chamber 202, avalve'seat member 204 in said chamber, a ball valve 206V and a sp'ring208 backed up by a-plugu210 for resilientlyv ,urgingV the ball againstthe valve seat. The valve 200 is of -identical construction and `is',therefore, not Vdescribed'in'.detailw.

Horizontal passageways ',212 and VV214 lead, respectively-x Y from thevalves 198 and 200 to horizontal pumping Y 1tchambers 216 and218containing pistons 220 and222.

A pair Vof vertical passageways 224 and 226 dischargeV fluid from thepumping chambers 216 vand'218 vto a pair of check valves indicatedgenerally at 228 and 230 which are of the same construction asA thevalve 198. Each of the check valves 228 and 230 communicates with anoutlet channel 232 discharging into a conduit 234.

In the pump 140 the Vpistons 220 and 222 within the pumping chambers 216and 218 areactuated by means disposed within the hollow interior of thepump housingl 154 and described as follows. A pair of bell cranks 236and 238 are pivotally mounted on the housing at 240 and 242 and have endportions 244 and 246 for engaging respectively the pistons 220 and 222;The eccentric cam 158 of the sleeve 66 with its bearings 160 and 162extendsbetween theends -24-4 and 246 of the bell cranks 236 and 238 foractuating the latter alternatively as the drill spindleA 32 is rotated.A A

1n the operation of the pump 140, hydraulic iluid under pressure entersfrom the pipe 192, flows` through the passagewaysY 190, 194 and 196,forces the check valves 198 and 200 open and enters the pumping chambers216 and 218. Since the pistons 220 and 222 are actuated alternately bythe eccentric cam 158 and its bearings 160 and 162, the uid enters thepumping chambers 216 and 218 alternately. Thus, on clockwise rotation ofthe spindle 32 from the position shown in Fig.- 1.0, the charging uidwill pass through the check valver 198 and thence into the pumpingchamber 216 during the time that the piston 222 is moving outwardlyduringits pumping stroke. The, uid entering the chamber 216 not onlyfills the chamber for the next pumping stroke of the piston 220 `butalso serves to force, the piston toward its innermost position. Thefluid pumped by the piston 222 flows from the pumping chamber,` 218through the passageway 226, forcesthe check valve 230 open and isdischarged through the passageway 232 intoV the pipe 234. Similarly, theiiuid flows from the pumping chamber 216 through the passageway 224,forces the check valve 228 open and is discharged through the passageway232 into the pipe 234, while at the same time the other pumping chamber218 is being filled and the other piston Y222 is being forced to itsinnermost position by the entering fluid.

The bell crank end portions 244 and 246 .which con-V tact the eccentricbearings 160 and 162 and the pistonsV 220 and 222 are formed to modifythe motion imparted to the pistons 220 and 222 in such a manner that thedischarge fluid is delivered from the channel 232 at a uniform ratewhich is substantially free from pulsations.

Variations in the rate of ydischarge of the pump 140 is provided for bymeans of a shaft 248 received Vin a suitable bore formed inthe pumphousing 154 and having an end portion which serves to limit the pivotalmovement ofthe bell cranks 236 `and 238 during the charging stroke ofthe pistons 220 and 222.' The position of the end of the shaft 248 withrespect to the bell cranks can be adjusted by'turning the shaft 248which is externally threaded near its upper end and engages internalthreads at the upper end of the shaftbore. If desired, a sealing ring250 may be provided in a circumferential groove 252 in the shaft 248. Yl.

The fluid delivered by the pump 140 passes through conduits and valves(described hereinbelow) into the bore 106 of the uid motorr103 whichdisplaces the ram Y drill head 22.' Since the `drill spindle 32 drivesthe pump 140 during the feeding movement of the ram drill head 22, any4reduction in the rate of rotation of the drill spindle,tas whenresistance to drill penetration occurs' (due to variation in materialbeing drilled,` or j due to the drill`becoming dulled, clogged withvchips' or expanded by heating) will cause a corresponding reduction inthe rate of fluid delivery bythe pump l to the duid motor and in therate of advancement of elimination of drill breakage o Control devicesThe next following paragraphs will describe, first, and in part only,two control valves forming part of the hydraulic system, and, secondly,a system of dogs, switches, solenoids, levers and links serving incooperation with the above noted two valves to control the movement ofthe yrarn drill head 22.`

A main control valve indicated generally at 254 extends lengthwise,within the hollow drill head carrier 16, as shown in Figs. 3, 7, 8, 9,19, 20, 22, 23, 24, and 25. The valve 254 includes a stem 256 slidablein two opposed aligned horizontal bores 258 and 260 formed,respectively, in two spaced housings 262and 264 attached to the' insideof the drill head carrier 16 and separated by a vertically extendingspace 266 spanned by an intermediate portion ofthe valve stem 256. Asshown in Figs. 22 to 25, the valve stem portion slidable in the bore 258of the housing 262 is` formed with four transverse detent grooves 268adapted to be engaged by a ball 270 under the urging of a spring 272seated in a suitable bore formed in the housing-262. As also shown inFigs. 22 to'25, the detent 270 serves to retain the valve stem 256 inany one of the four operative positions of the valve 254, namely, rapidapproach (valve stem atextreme right, as shown in Fig. 23), feed (valvestem at central right, as shown in Fig. 24),Y neutral (valve stem atcentral left, as shown in Fig. 22), and rapid return (valve stem atextreme left, as shown in Fig. 25).

For moving the stem 256 `of the valve 254 between` to the inside end ofthe shaft 276 and carries at its i lower end a pin 286 rotatably fittinga vertical grooveY 288 formed in the intermediate portionof the valveystem t 256 spanning the space 266. i Further, the inner halfof the shaft276 is restricted, and between the radial shoulderdefined by thisrestriction and the lever 284 another lever, 1 290 is pivotally arrangedon lthe shaft 276 by meansof a sleeve 292. The upper end of this sleeve292 carries an arcuate gear rack 294 which meshes with a plane gear rack296 slidable in a horizontal slot 298 formed..

in the drill head carrier 16. Lengthwise displacement:-

of this rack 296 will swing the lever 290 about, its pivot and thereby(as disclosed in detail hereinbelow) move the lever V284`and the valvestem 256-fromone to another of its operativepositions. o

For effecting such displacement, fthe rack 296 carries an upstandingfinger 300 adapted to be contacted by a dog (described hereinbelow) anda solenoid operated mechanism is also provided, described as follows. Asshown in Figs. 3, `8, 9, 19 and 20, `the drill head'carrier 16 hasattached to one side thereof aligned opposed solenods 302 and 304. eachoperatively `connected to the lowerY outwardly offset end of a lever 306fulcrumed on` the drill head carrier 16 `at 308. The short upper arm ofthis lever 306 is slotted, and a pi'n 310 projecting horizontally fromthe rack 296 fits in this slot so that movementtof the lever 306 underthe inuence of either, of the solenoids 302 or 304 will be translatedinto horizontal displacement ofthe rack 296. Specifically, the.`

solenoid` 302 serves to initiate forward movementI of the drill head 22and the solenoid l304 to initiate? described hereinabove controlsactuation Ofthcretum return movement of the drill head 22, as will bedescribed in greater detail hereinbelow. Further, `the switch 102.`

i acosta-af?- solenoid 304 along with another switch` 312 actuated by asafety overloadvalve 314 (described in detail hereinbelow) which isresponsive to high hydraulic fluid pressure on feeding of the drill head22 against excessive resistance.

The means whereby swinging of the lever 290 moves the lever 284 isdescribed as follows, with reference to- Figs. 19, 20 and 2l. Opposedaligned actuators316 and 318 project from bores 320 and 322 formed inthe housings 262 and 264 into the space 266 and contact the lever 284for shifting the latter. These actuators are hydraulically operated bypressurized uid owing into and out of the bores 320 and 322throughconduits 324 and 326 from bores 32S and 330 under the control of pilotstems 332 and 334 shiftable in the latter bores bythe action of thelever 290`which is contacted by the ends of the pilot stems projectinginto the space 266l under the urging of springs 336 and 338 seated inthe bores 328 and 330. Fluid under pressure is admitted into the latterbores through conduits 340 and 342, whilev passageways 344 `and 346 areprovided for drainage. The pilot stems '332 and 334 have restrictedmiddle por tions, so that they can be shifted between a iirstl position(-With the springs 336 or 33S compressed) where pressurized iiuid canilow across such a constricted pilot stem portion from the conduit 340or 342 into the conduit 324 or 326 and a second position (with thesprings 336 or 338 expanded) where iiuid can drain from the conduit 324or 326 across such a constrictedpilot stem position into the conduit 344or 346. Thus, when'the rack 296 is displaced and thelever 290 is causedto swing, the latter depresses one of the pilot stems 332 or 334,pressurized uid is admitted into one ofthe bores 320 or 322 to move oneof the actuators 316 and 318, and one of these actuators swings thelever 284 to displace the valve stem 256 of the control valve 254.

As` disclosed hereinabove, the ram drill head22y can be displaced atrapid approach rate, at feed rate and ataV rapid return rate. Themechanical devices for controlling these rates and directions ofmovements are described as follows, reference being made to Figs. 2, 3,7, 8, 9 and 19. The ram drill head 22 includesa lateral extension 348sliding on thebed 24 and formed with a longitudinal upwardly open slot350 having a cross-sectional Yconfiguration of inverted T-shape. A resetdog 352-is adjustably clamped to the drilll head extension 3.48 by ascrew 354 having a head disposed in the bottom rockr shaft 404V which isof square cross-sectional fornr.

between the said brackets and also has a feed set dog of the slot 350. Apin 356 projects laterally'from a.

bore 358 in the reset dog 352 under the urging of a spring 360 seated insaid bore. A latch dog 362i is adjustably clamped to the. drill headextension248 by a screw 364 having a head disposed in the bottom of theslot 350. An ann 366 extends in a diagonal slot 368 formed on top of thedog 362, having oneend pivoted around a bolt 370 and the other'endprojecting laterally from the dog 362 under the urging ofa spring 372seated'l in a bore 374 formed in said arm and receiving a pin 376projecting therefrom intocontact with the wall of the slot 368.

At the ends of the lateral drill head extension 348 laterally projectingbrackets'380. and 382 are attached'- thereto by means of bolts 384 and385V having heads.

disposed in the bottom, of the slot350.` These brackets have dependingend portionscarrying a slip rod 386'of square cross-sectional form. Aslip dog 388 is slidably threaded over the slip rod 386. Specifically,the slip dog 388 is formed with an internal vertical'bore 390in which isseated a spring 392 urging` a shoer394l against the rod 386. Further,the slipV dog 388 isformed with aA depending tongue 396 providingia camsurface 398:` Note that the slip rod 386 carryingtheslip dog Y388'rnoveswith the ram drill head 22.

A.rst ofrear upstanding bracket 400i extending-from.

the. drill head carrier standing bracket, 402 also extending; from. the;drillhead 16; and aasecondor: fronte up` 406 threaded over itssquarerportion. The positiono' the feed set dog 406 is adjustably fixedvon the roclfcf' shaft 404 by means of a screw-468. The shaft 404 mayV4be rocked byA means described as follows. A pinion 410 mounted on thesquare portion of the shaft- 404" meshes with a rack 412 slidablydisposed in an appropriate bore 414 extending transversely through thebracket 402 above the shaft 404. An upstanding pin 416 on' the rack 412extends through a slot 4,18 communicating with the bore 414 andpermitting displacement therein' of the pin 416. For'effectingdisplacement of said pin, and thereby also of the rack 412, a lever 420is fulcrumed'` on top of a vertical projection 422 from the bracket402;` The lever has one end slotted at 424, and the pin 416` the lever420. The other endv ofV the latter lever is:

Yformed withV a projection 426. Thus, when the arm 366' of the latch dog362 or the pin 356 of the reset dog; v

352y contacts the projection 426 of the lever 420, the latter will bepivoted, the pin 4116 and thereby also the rack 412l will be displaced,and the pinion 410 and" thereby also the shaft 404 will be rocked.

Other means for rocking the shaft' 404 are also pro-A vided; Thus, infront of the bracket 402, the shaft 404"- carn'es ay sleeve 428 providedwith a control handle 430, whereby the 4shaft 404 may be rockedmanually. i

At its end the sleeve 428 in the rock shaft 404 carries: an inturned arm432 provided at its end lwith a transverse;l bore receiving a pin 434having a head at each end, A spring 436 between the arm 432 and theforward headf of the pin 434 serves to bias the pin 434' into the posi:tion shown in Fig. 7. 1 Y f TheV shaft 404-is rockable between a firstposition illus-e4 trated in Figs. 3, 7 and l0 wherein the feed set dog406.1 extends vertically and the .pin 434'is aligned with another"Y pin442 described hereinbelow, and a second position wherein the lower endof the feed set'dog 406 extends'inwardlyV and the pin 434 is brought outof alignment` with:y the pin 442. To hold the rock shaft 404fyieldablyiir; either one of these two positions, a detent pin4381eceived in a suitable vertical bore in the bracket 402 engageseither of two grooves or recesses formed in 'thee stem 428 under theinfluence of a spring 440 se'atedirry said bore, as shownein Fig. 3.

The above noted bolt or pin 442 extends through ay threaded bore in aforward and downward extension^444 ofthe bracket 380 and may be adjustedlengthwise there-V in by turning.

Function of controldvces The functionofthe above describedmechanismsfor: controlling the movement of the ram drill head 22 isde:scribed as follows. At thel start of a drilling operation, the valve 254is in neutral position, with the valve stem in its left centralposition. l position assumed in the last step of the preceding drillingoperation, .e., the.pin.43f4 is out of alignment with the pin-442 andthe feed set dog 406 has its lower end in: clined inwardly. Furthenatthe end of the last previous drilling operation, the slip dog 388 hasbeen pushed allVv The rock shaft 404 is in the] Next, the slip dog 388.I described above to initiate'feeding movement of the ram drill head 22,but this time only after rapid approach. has Y continued to the.` pointwhere return movement was started. N ote that the slip dog 388 was heldbyY the' and thereby admits pressurized fluid behind the actuator 332 sothat on outward movement of the actuator 332 against the lever 284, thelatter will displace the valvev stem 256 toits extreme right position asshown in Fig. 23.` Note that Fig. 19 is la view. from the opposite side,so that there the rapid approach position of the valve stem 256 isshownas the extreme left position. d

, As the ram drill head 22 moves forward on initiation of drilling, theprojecting arm 366 of the latch dog362 contracts the projection 426 ofthe lever 420 and swings the` latter whereby the rack 412 is displacedinwardly and the pinion 410, and thereby also the shaft 404, are rotatedto bring the latter into the position where the two pins '434 and 442are aligned and the feed set dog 406 assumes a vertical position.

3 Whichever way drilling was initiated, the lever 280 was swung over tothe left, and, as a result, its projection 282 no longer extendshorizontally butrather upwardly and into the path of the slip dog 388.Hence, as the latter moves forwardly with the slip rod 386, the camVsurface 398 of the slip dog 388 engages the projection 282 of the lever280. The proportions and conligurations of the projection 282 and thecam surface 398 are so balanced, and the pressure of the spring 392 inthe slip dog 388 (which spring pressure controls resistance againstlslipping of the dog 388 on the slip rod Y386)r is` so adjusted, thatupon such contact of the cam surface 398 of thei dog 388 with theprojection 282, the lever 280 will be swung to the right, to bring thevalve stem 256 into feed position, i.e., into central right position,and so that thereafter the dog 388 will be held against further movementby the projection 282.l Then the rod V286will sliderthrough the dog 388as the latter is held stationary. It will be understood that,Y before adrilling .operation is initiated, the dog 388 is positioned on the sliprod 386 at Y,appoint selected so as to cause initiationoffeedingmovement of the ram drill head 22 after rapid approach over apredeterminedV distance. d Y Y When, as feeding progresses, resistanceto feeding or to drill driving torque becomes excessive and, as avrresult, either the` switch 102 is actuated by the torque responsiveoverload release safety clutch including the collar 98 or the switch 312(which is arranged in parallel with jthe switch 102) lis actuated by thesafety overload relief valve 314 responsive to excessive fluid pressure,then thereturn solenoid 304 is energized and by the means abovedescribed shifts the lever 284 and therebyT the valve stem 256 to rapidreturn position, i.e., extreme left position;` YOn this returningmovement, the slip dog 388 retains its position on the slip rod 386,which, of course,

shares the return movement of the ram drill head 22.

At the end of the return stroke, the pin 442 carried by the arm 444 ofthe bracket 380 on the lateral extension 348 of the ram drill head 22contactsthe pin. 434 carried by the inturned arm 438 extending from thesleeve 428 of the rock shaft 404, moves the pin 434 of the spring 436against the upstanding finger 300V of the -rack 296 and thereby dsplacesthe latter to turn the lever 290 to move the pilot stem 332 admittingpressur ized uid behind the actuator 316 so that the lever 2.84 againmoves the valve stem 256 to rapid approach position (extreme right). 5again actuates the mechanism lever projection 282 throughout theprevious feeding stroke while the rod 286 was allowed toslidevtherethrough. Thus,'the dog 3788,v has been displaced totherearwardly or to the right-.on the rod 286 over a .distance-Icorresponding "to the .forward movement of the ram drill head 22 duringthe next precedingfeeding strokey of'zthe `ram drill head."

against the. force 12v In the manner indicated, a series of rapidapproach, feed,` andreturn movementsare performed until a predetermineddrilling depth has been reached. At` that time, the ram drillhead isreturned to its starting position as follows. Thepin 356 of the resetdog 352 con` tacts the projection 426 of the lever 420 to move the rack412 and to rotate the pinion 410 whereby the'rock shaft 404 is shiftedto bring the pin 434 out of alignment with the pin 442 and to inclinethe lower end of the dog 406 inwardly. At almost the same time, the pin`356 of the reset dog 352 also contactsthe upstanding arm 300 of therack' 296 whereby the valve stem 256 is brought to rapid return position(extreme left) as described above; It will thus be noted that byadjusting position of the reset dog 352 the drilling operation can beterminated` at any predetermined depth. As the ram drill head 22 movesrearwardly iniits rapid return, the inturned lower end of the feed setdog 406 contacts the slip dog 388 to hold the latter as the rod 386slides therethrough. Since the pin 434 now is not interposed in the pathvof the pin 442tl1e upstanding finger 300 of the rack 296 is notcontacted, the `rack 296 is not moved, and the return movement is notterminated by another rapid approach stroke of the ram d rill head 22.Instead, the rapid return movement is terminated by the piston 108 beingheld against further4 rearward movement by the cap118 of the uidmotor.103. Thereafter, the control lever 280 is manually moved into theposition corresponding to the neutral position of the valve 254.

If at any time during a drilling operation it is desired 1 to interruptthe same before drilling is completed, the lever'430may be swung to rockthe shaft 404 into the position where ithe pin 434 is no longer` alignedwith the pin 442,*either of the switches `102 or` 312 may be actuatedmanually and when the rapid return movement thus initiated hasbeenterminated, the control lever 280 may be moved to neutral position.A new drilling operation may then be started.

Hydraulic system The mechanical aspects of the movements ofthe ram'drill head 22having been described hereinabove along with the plungerpump 140,` the hydraulic system ofthe machine of the present inventionandits functioning willV now be disclosed. This disclosure will include,first, a description Yof certain valves and other flow regulatorsforming part of this hydraulic system and, secondly, a description ofthe hydraulicy system as a whole.

Y. Reference is made to the diagrammatic representation of the maincontrol valve 254 in Figures 22 to 25.` As shown, that portion of thevalve stem 256 slidable within` the bore` 260 in the housing 264includes four enlarged` communicating, respectively, with fluid channels460,1 136, 464 and 466, 138 and 470. As will be discussed furtherhereinbeiow, conduit, 464 is connected to,a source of pressurizedhydraulicgfiuid; conduits 436 and f 438 are connected to the Vfluidmotor `103; conduits 460 and 470 are connected to a reservoir forhydraulic uid; and conduit 466`is connected to the conduits 340 and 342leading to the'bores` 328 and 330 ,of the pilot stems 332 and 334. VThedirection of ow,ffif any, of hydraulic fluid through the valve 254 inthe various operative posi` tions of the valve stem 256 is as follows.When the valve stem 256 is in rapid `approach position (extreme right,as shown in Figure 23), uid under pressure enters the valve 254 fromconduit 464, ows along the `reduced valve stem portion 456 'and isdisharged through conduit 138 for ow to the uid motor `103. At the sa'metime,

' uid discharged from the uid'rnotor 103 enters the valve 254 throughconduit 136, ows along the reduced valve the housing 474 and capable,

460v for` ow tothe reservoir.- Whenlthevalvestemv 2561 lsin feedposition (centrali right, as shown in Figure 242); all interconnectingpassages within thevalve are blocked, so that no flow can occur betweenthe conduits 460, 136', 464, 138 and 470. The enlarged valve` stemportions 448' and 450 block any ow from the inlet conduit 464 and alsoany ow into orl outof the conduits 136 and 138, The drain conduits-460and 470are blocked and isolated; by pairs ofV enlarged valve` stemportions 446 and 448, on theV one side, and 459 and 452,` on the otherside. Similarly, whenthe yvalve stem 256 is in neutral orstop position(central left, as shown in Figure 22), all interconnecting passageswithinthe valve are blocked, so-thatino flow can occur between conduits460, 136, 464, 138,.v and 470. Whenthe valve stem 256 is in rapidreturnr position (extreme left, as shown in Figure 25),

pressurized uid enters through conduit 464, ows along therestrictedvalve stem portion 456 and is discharged through conduit 136tothe huid motor 103. Fluid draining from the uid motor'103 enters thevalve 254 through conduit 138, ows along the restricted valve stem portion 458 and is discharged through conduit 470 tothe reservoir. However,at all times flow -f of pressurized 'v iiuid is possible from theconduit 464, around the reducedvalve stemportion 456 and out through theconduit` 466;to the pilotstem bores 328 and 338.

T;he above noted safety overload valve 3-14 is shown in detail inFigures 15, 16 and 18. The valve 314 extends along with a sequence valvegenerally indicated at 472A Within one and the same housing 474 andthese two valves have a commonk inlet port'476receivingpressurized'fluid from the conduit1234. The bore of the valve314 extends atright angles to the. port 476 and includes a-iirstrestricted portion 480 and a second expanded portion 482, a; valve seat484 being dened at the juncture of-.these twofvalve boregportions. The'valve-314 further includes afstem 48:6 havingaface urged against thevalve seat 484- Y by a spring 488 seated in the enlarged bore portion482. The valve stem portion within the restricted valve bore 480 isfluted to permit the hydraulic fluid to exert pressure against4 thevalve face and to force the latter on the valve seat 384 if and when thehydraulic pressure is strong enough to compress the spring 488. In thisevent, the

uid iiows into the expanded bore portion and is discharged through acentral opening into a conduit 490. Further-,the Avalve stem 486isprovided with an extension rod 492 projecting through a cap 494outwardly from when the face of the valve stern 486 isdisplaced from thevalve seat 484, of actuating theswitch 312. The valve 314 functions asan overload or relief by-pass valveresponsive to excessive hydraulicpressure and also actuating the switch 312 to initiate re turnof the ram`drill head `22'from the work piece.

The sequence valve 472 includes a restricted bore portion 496 and anexpanded'bore portion 498, a valve seat 500vbeingde1ined at the`junction of these two bore portions. A fluted valve stem 592 is turnedwith a face urged against the seat 500 by a spring 504. When the valveface is displaced from the seat 502, ow of hydraulic Huid into theexpanded bore portion 498 takesplace, and the uid isdischarged through alateral aperture into a conduit. 506 which in turn discharges into theconduit 138, asv explained .hereinbelow. The function of the sequenceva1ve472 is to determine (by the setting of the springV 5 04.)anminimum, pressure for now of hydraulic fluid therethrough. t

T he valve housing 474 also includes a channel 508 having Vtherein ascrew plug 510 formed with a restricted oriiice slztherethrough. Fluidenters thechannel 508 froma conduit 514 (which is a branch ofthe conduit464, asL explainedY hereinbelow) and is discharged into aconduit 516.lThe function ofithis structureisdisclosed hereinbelow. t

528- having a bore 530 ittedwith a stem 532. The bore'-v 53,0risVconnected by appropriate parts with an inlet conduit 5,34 (which is abranch of the conduit 516, as exi plainedhereinbelow), with theconduit522 (which func.V

tionsv as an outlet conduit) and with a drain conduit 538.

AY springf540-urges the valve stem to the left (as shown in Figurel4).The valve stem.5327 includes a restricted?- portion 542 and disk shapedenlarged end portion 544L on the rightside extending in acircumferential grooveA 546 in the'bore, 53). This disk 544 blocks flowof fluid` through the` bore 530: when the: stem 532 .is displaced' to`the left by the spring 540. The valve 526.isfoperatedi` by, a Solenoid5.48 having ainger 550 which, whenthe solenoidisenergized: pivots. tomove the valve stem 532 to the right, permitting fluid from the conduit534 Vtotiow around the restricted valve stem portion and out of the;valve throughthe conduit 522, access tothe drain conduit 538 beingblocked'by the disk 544. The lbore 530Lis closed by a cap 5,52 whichalso carries the fxedend-ofthey spring 540. Thefunction of the chargecontrol vals/e526 willgbe discussed hereinbelow. Y

T he solenoid 548 isoperated by a switch S54 shown inl Figures 1 and 6which in turnis actuated by a finger S56-carrying at its end a roller558. As shown, the switch.l 554'is mounted on the drill head carrier 16andthe rollen; contactsione sidel of the ramtdrill head 22, beinglifted: toactuate the switch;` 554 by a cam 560 on the ramdrill. head22'locatedso that on rapid approach of the ram.'Y drill. head the switch554 willbe actuatedbeforeA theram:

drill head 2 2 begins feeding movement. On rapid return' of theramdrillhead, the; switch` 554 is again actuated,` thefinger 55;6 .beingurged against the ram drillhead-ZL.

by, a spring-(not shown).

The hydraulic system as a whole willV now be ,described',. referencebeingy made to the purely diagrammaticreprez,

sentationin Figure 26. A s shown, this hydraulicsystein includes a tankor reservoir 562 for hydraulic fluid whichv iswithdrawn therefromthrough a conduit l564 by apumpj 56,6ffor pressurizing and subsequentdischarge througha. conduit 568. The pump 566 is` suitably a gear pumpoff' the. type shown in Figures-4 and 25 through 29 of-my-co-l pendingapplicationSerial No. `437,067, tiled on June 16 1954, and 'entitledMaterial Working Apparatus, al

though other` gearpumps; or the like may also be em-l ployed forpressurizingl the hydraulic iiud ahead of the; pumpV 140. The preloadinggear or other pump puts the, hydraulic fluid under considerable pressureand this mate?.v rially increases the Vefficiency of the pump 141). Thisre; sultsfrom, thefact that the fluid entering the pump 148A hasbeenslightly compressed so that it cannot be further` compressed anVappreciable amount by the pumpk 140;

While, of course, the amount by which unpressurized fluid', Vmight becompressed by the pump is small (about4 OI05%'), such compression isoften suiiicient to Vintroduce-t undesirable variationy in the movementVof the ram drill;-

head 22. In addition, the preloading of the charging iiuid substantiallyeliminates any possibility ofiuid leaking;

back through` the check valves offthe pump Ii4t-during pumping strokesofthe pump pistons.

The pump 566 delivers4 the pressurized uid through; tlie conduit-568 toa relief valve 576 which acts to limita;

therma'ximum pressure delivered by the pump 566, excess,

' uid being kdirectediback, to the reservoir 562 through aY conduit 572.The drain conduit 538 from the chargey control4 valve 526 alsodischarges intothis-conduit 572.

Fromfthev relief valve 570 the.v pressurized fluid ows through a conduit574 toa pressure reducingvalve 576.

It shouldgbeiunderstood that the reservoir Y5452,* the pump- 5.66;the;,valves5'l0zand.576iand the conduits 564, 568;"

572 'and 574 are not included-inthe machine shown in Figure l, butare-provided and mounted separtely` therev from to function as a sourceof pressurized fluid for a pluralityof machines of the'type shown inFigure l.

In each such machine there is provided a pressure re-V ducing valve (notshown) similar tovalve. 576 and connected to the relief .valve 5770 in`parallel with the valve 576 by-suitable conduitsY (not shown): Thesepressure reducing valves connected in parallel to the relief valveinsure that each drilling machine will receive an adequate supply offluid under suicient pressure.

Each drilling machine is provided with suitable drainv conduits (notshown) which direct fluid yback to the reservoir562 similarly to thedrain conduits of the machine of Figure 1, as disclosed hereinbelow.Ifonly aV single drilling machine is ever to be operated by pressurizedfluid supplied from the pump 566, the valve A576 may be omitted.

From the pressure reducing valve 576, pressurized fluid flows throughconduit 464 directly to the main control valve 254 for flow therethroughand through conduits 136 or 138 (when the valve 254 is in rapidapproachvor rapid return position)V to the fluid motor 103. Note also that (whenthe valve 254 is inl rapid approach or rapid return position) either theconduit-1136 or 138 serves as a return conduit for theuid motor 103 tothe valve 254, the returned fluid being discharged veither directlythrough the conduit 460 to a drain conduit 578 discharging into thereservoir 562 or indirectly through conduit 470 into the conduit 490which in 'turn dis charges into the conduit 578.

Note further that presf the ram drill head 22 forward ataV ratedependent only on the delivery of the pump 140. Forward movement of thepiston 112 of the fluid motor 103 `forces fluid, from the cylinder 104.into the conduit 136 from where it flows into conduit '.'80 and throughthe valve 526, conduit 522, strainer 518 and conduit 192 back to pump140, where the fluid is Vrepressurized` and again dischargedv throughconduit 234, thus completing the closed circuit. An amount Yof fluidsulcient to make up for the extension of the piston rod 112 from thecylinder `104 on continued feeding movement is admitted to the lowpressure surized lluid is always supplied from the conduit 464 throughthe main valve 254 to the iconduit 466 having the two branch conduits340 and 342 connected to the pilot stems 332 and 334 connected by theconduits 324 and 326 to the actuators 316 and 318. The drain conduits344 and 346 from the pilot stems v332 and 334-`dis`charge into the drainconduit 578. Thus, thepressurizeduid for effecting rapid approach andrapid return of theV 4ram drill head is supplied directly from the pumpi566 under the control of the main valve 254.

side ofthe above noted closed feed circuit .from conduit 514, orifice512 and conduit 516, the orifice 512 functioning as a metering deviceand being effective to isolate the closed Yfeed circuit from thepressurized fluid suppliedfrorn the pump 566.. As ncted hereinabove, the

sequence valve 472 insures that no fluid will flow in the closed feedcircuit unless sufficient pressure is developed by the pump 140 toeffectv proper` feedingV action and to` eliminate anypossibilitythatiluid would `flow over the ball valves of the pump 140 into thefeedfcircuit without being properly metered by the pump 140. `As alsopointed out hereinabove, the safety relief valve protects the feedcircuit fromundesirably high pressures, excess fluid being drained offthrough conduits 490 and `578 "and Vthe switch 312 beingA actuated toinitiate rapid return` A of the ram drill` head 22.

When the main valve 254 is in neutral rposition and the charge controlvalve 526 is closed, the solenoid548 being deenergized, no hydraulic owtakes place in the machine. Flow of pressurized fluid from the conduit464 through the valve 254 into the conduits 136 and 138 is blocked, andflow from the conduit 466 and. its

branches 344 throughV the pilot stem 332 isr likewise blocked.V Flow ofpressurized fluid through the conduit 514 (which branches olf from theconduit 464), through the restricted orifice 512, through the conduit516 and through the conduit 534 (which is a branch of ithe conduit 516)and through the valve S26-is blocked due to the fact that the valve 526is in closed position. A conduit S80 branching from the conduitv 516 andcommunicating with the conduit 136 is likewise blocked, for no dischargeinto and through the closed valve 254` is possible, either directly fromthe conduit 136 or through. the fluid motor 103 and thence through the`conduit `138. Further, the conduit 506 is connected to the conduit 138,but flow from the conduit'138 and the conduit 506 through the valve 472is impossible, the valve 472 being a one-way check valve. It may Abenoted, in this connection, thatiwhen the valve 254 is in rapid approachposition, a small amouknt of the pressurized fluid flows through theconduit" 514, the restricted orifice 512, the conduit 516 and theconduit 580 into the conduit`136 where it rejoins the bulk of the fluidflowing `to the main valve 254 through the conduit 136. f

In the last stage of the'rapid approach movement of the ram. drill head22, the switch 554 is actuated as its` finger 556 is lifted by the cam560 and the solenoid 548 is; energized, whe'rebythe chargecontrolvalve`526 is General function of the machine The machine of the presentinvention is particularly adapted for usesrsuch as drilling oil holes584 in au` tomobile crankshaft'582 shown in Figures 27, 28, 29 and 30.For this purpose a number of drilling machines such as the machine 10 ofFigure l may be set up to drill simultaneously all the oil holes584 in asingle crankshaft 582, pressurized fluid being supplied to allrthemachines from a single gear pump 566, as shown inFigure 26.

Before drilling is initiated, the dril head carrier 16'of each machine10 is adjusted to a proper distance from the workpiece by a suitabledisplacement on the guideway 14. Further, the slip dog 388 of eachmachine 10 is adjusted on its slip rod 386 toinitiate feeding movementof the ram drill Vhead 22 just before the latter contacts. theworkpiece, and the reset dog 352 of each machine 10 is also adjusted toterminate the drilling cyclevof` each machine 10 when a hole of desiredpredetermined depth has been drilled. When thereafter drilling' isinitiated, eachmachine 10 will complete its drilling cycle independent'yof the other machines. The ram drill head 22 of each machine 10` will bewithdrawn from the'workpiece ,whenever excessive torque or thrustresistance `is encountered in drilling` a particular oil hole 584, whichwil vary from machine to machine and as betweenthe various 'ho`e's beingdrilled,

since all drills 40 are not equally sharp and do not wear down at thesame rate, and since the material of the crankshaft 582 will exhibitlocal variations in hardness.`

By way of a specific example, typical data'illustrating thev timerequired for drilling of oilV holes in an automobile crankshaft aregiven as` follows: T Vei material -of construction was AISI-1045 forgedsteel; thedrill size,`

Vs inch diameter; the drillspeed, 6 88 revolutions pe l' minute and 45vsurface feet per minuterthe feed rate, 5.07 'inches `per minute and0.0076 inch perdrill revolution;V

17 and the total drilling depth, 2% inches. The drilling required fourseparate drill entries into the workpiece. The elapsed time (in seconds)is tabulated as follows:

Total 30.1

Another example will illustrate the depths drilled before occurrence ofoverload and withdrawal of the ram drill head 22 from the workpiece. Theconditions of drilling were similar to those described in the precedingparagraph. The `data are tabulated as follows:

rille above described specific examples or tests are merelyillustrative. Many details of the above disciosed specic machine may bevaried without departing from the principles of this invention. Itistherefore not my intention to limit the scope of this applicationotherwise than necessitated by the scope of the appended claims.

The invention is hereby claimed as follows:

l. In a metal working machine comprising rotatably drivable tool spindlemeans, an electric motor for rotating said spindle means, a fluid motorfor actuating said spindle means longitudinally for feeding a cuttingtool into said work piece and for returning said spindle means, positivedisplacement variable delivery hydraulic pump means in alignment withsaid spindle means, said pump means including a drive shaft which is aportion of said spindle means for actuating said spindle meanslongitudinally at a feeding rate controlled positively and directly inaccordance with the rate of rotation of said spindle means, and meansresponsive to a predetermined torque experienced bysaid spindle meansduring the feeding thereof to initiate return of said spindle means.

2. A metal working machine comprising rotatable rigid tool spindlemeans, an electric motor for rotating said spindle means, a fluid motorfor actuating said spindle means longitudinally for rapid approachtoward a work 18 Y Y means, and resilient means responsive to apredetermined torque experienced by said spindle means during thefeeding thereof to initiate return of said spindle means.

3. A metal Working machine comprising a spindle including rotatablysupported tubular means and an elongated rigid member for supporting atool axially slidably and rigidly non-rotatably supported in said means,a iluid v motor for actuating said elongated member longitudinally forrapid approach toward a workpiece, for feeding a cutting tool into aworkpiece, and for returning said member from a workpiece, means forsupplying lluid to said fluid motor to effect selectively rapid approachand return of said member, positive displacement variable deliveryhydraulic pump means on said rotatable tubular means and including adrive shaft which is a portion of said rotatable tubular means andconnected with said fluid motor for actuating said elongated memberlongitudinally at a feeding rate positively and directly controlled inaccordance with the rate of rotation of said elongated member.

4. An apparatus, as defined in claim 3, including a drive mechanism forrotating said tubularmeans said drive mechanism comprising a rotarydriven member freely disposed on said rotatable tubular means, and meansresiliently engageable with said driven member for driving said tubularmeans and responsive to a predetermined torque experienced by saidrotatable tubular means during a workpiece machining operation toinitiate return of said elongated tool supporting member.

5. An apparatus, according to claim 3, wherein said elongated membercomprises a rst elongated splined portion disposed within said tubularmeans, and a second elongated portion projecting axially outwardly ofsaid tubular means, said iluid motor including an elongated hydrauliccylinder disposed adjacent and parallel to said second elongatedportion, a piston slidably disposed f within said cylinder, an elongatedrod having one end connected with said piston and an outer endprojecting from said cylinder, and slide means secured to the outer endof said rod and rotatably receiving and supporting said second portionof the elongated member, said slide means including means retaining saidelongated member for axial movement with the slide means.

6. In a metal Working machine comprising rotatably drivable tooolspindle means, a fluid motor for actuating said spindle meanslongitudinally for feeding a cutting tool into a workpiece and forreturning the spindle means, and positive displacement variable deliveryhydraulic pump means in alignment with said spindle means and includinga drive shaft which is a portion of said spindle means for actuating thespindle means longitudinally at a feeding rate positively and directlycontrolled inaccordance with the rate of rotation.

References Cited in the tile of this patent UNITED 'STATES PATENTS1,911,132 Macomber May 23, 1933 1,911,138 Clute et al. May 23, 19332,454,235 Tomek Nov. V16, 1948 2,559,125 Lee July 3, 1951 2,562,170Busemeyer July 31, 1951 2,643,555 Steibel June 30,1953

